This document describes the AT commands used to control the modem subsystem and 3GPP release 14 LTE-M and Narrowband Internet of Things (NB-IoT) modem firmware in nRF9131 and nRF9161 (nRF91x1). The AT command API enables modem control for firmware running in the application core on nRF91x1.
The AT command API can also be exposed on one of the nRF91x1 serial interfaces by programming appropriate firmware in the application core. The nRF Connect SDK contains examples of such proxy firmware that can be run stand-alone or as part of other firmware functionality in the nRF91x1 application core. The stand-alone example is called at_client. This way, an external MCU or computer can get access to the modem API either exclusively or in addition to application firmware running on the nRF91x1 itself.
The AT commands described in this document apply to all versions of the nRF91x1 module hardware. If a command applies only to a specific version of the module hardware, it is mentioned in the command description. The module hardware version is printed on the module label.